Furnace



' PfH. RICHARDS.

PURNAGE. N0. 517,627.l Patented Apr. 3. 1894.

' UNITED STATES PATENT GFFICE.

FRANCIS H. RICHARDS, or HARTFORD, CONNECTICUT, YASS'IeNoR rro ECKLEY R.CoXE, or DRIFToN, PENNSYLVANIA.

FU RNAC E.

SPECIFICATION fel-mag part of .Letters Patent No. 517,627, dated Aprile, 1894.

Application led February 20, 1894. Serial No. 500,888. (No model.) i

To a/ZZ whom it may concern.-

B e it known that I, FRANCIS H. RICHARDS, a cltizen of the UnitedStates, residing at Hartford, in the county of Hartford and State ofConnecticut,have invented certain new and useful Improvements inFurnaces, of which the following is a specification.

This invention appertains to furnaces and relates to methods orprocesses forthe economical burning of coal and-other fuel,

and to apparatus for carrying out the process, whereby the lower andcheaper grades of coal may be burned with economy and efficiency andwhereby the formation of clinkers during the combustion of the coal isreduced.

In the drawings accompanying and form- 1ng a part of this specification,Figure 1 is a sectional side elevation of a furnace embodying apparatusadapted for carrying out my present invention. y Fig. 2 is a verticalcrosssectional view taken on the line ot-a, Fig. 1, showing the parts attheleft hand of said line, as seen from a point at the lright-handthereof. p

Similar characters designate like parts in all the figures.

For the purpose of illustrating ther application and utility of mypresent invention, I`

out the presentprocess as applied to a furnace similar to the onedescribed in LettersV Patent of the United States,/No. 499,716, grantedto E. B. Coxe J une 20, 1893, to which reference may be had. It will beunderstood, however, that the objects of my invention may be attainedwith any form of furnace in which the fuel has a traveling movement inthe furnace-chamber, whenV said furnace is provided with apparatuscapable of carrying out my improved process; therefore it is not desiredto confine this invention to any particular form of furnace, nor to aparticulary kind of grate-mechanism therefor.

The furnace herein described is shown having a fuel-traveling grate andmeans for actuating the same, and has the usual inclosing walls at thesides and ends thereof, and is also shown provided with the ordinaryroof, S.

The side-walls are designated by 2 and 4,

5o respectively, the front end-wall, 3, rear wall,

8, and bridge-wall 7. At the forward endof the furnace this is providedwith the usual fuel-hopper H from which fuel is admitted to thefurnace-chamber through the inclined chute or opening 5 in a well-knownmanner. In the form herein shown, the grate is in the nature of anendless chain-grate, designated in a general way by G, and comprisingthe upper and lower runs 10 and 11, respectively, said upper runconstituting the furnace-floor under which is located the air-blastapparatus, which, in the preferred form thereof herein shown, comprisesthe successive airblast chambers a, b and c, arranged according to theinvention described in the aforesaid Letters Patent No. 499,716. Saidair-blast apparatus is supported by some suitable connection with theside-walls2 and 4of the furnace.

The air -blast chambers a, b, and/c, are shown provided with air-supplypipes, a', o and c', respectively, in which may be placedregulator-valves, ct, b and c, respectively, for independentlyregulating the air-blast in the successive air-blast chambers a, b andc. Said air-supply pipes may be furnished with air from a blower (notshown) substantially as described in the prior Letters Patenthereinbefore referred to.

For actuating the fuel-traveling grate this is herein shown carried bychain-wheels, 12 and 14, which are supported on shafts', 13 and 15,respectively; and for revolving one of the shafts and thereby actuating`the grate, said shaft 15 is shown provided with a worm-wheel, 40, whichmeshes with a worm, 4l, on the driving-shaft 42, that is supported inbearings 43 and 43', and isprovided with a driving pulley, 44, that isdriven by power from any suitable source, not shown.

The features j ust described, relative to the elements of the furnaceproper, are fully described in the patent hereinbefore referred to, andconstitute, in their particular con- ICO tendency to elinker is, in somecases, greatly counteracted by subjecting the burning fuel to combinedair-and-steam blasts; it is also found that the ignition of the fuel isgreatly accelerated by a dry-air blast, and that during the latterstages of combustion, the application of a dry-air blast to the fuelcauses a more complete combustion of the fuel;` and it is one of theprincipal objects of my present invention to furnish a process wherebythe fuel is subjected to a dry-air blast during its ignition period andduring the latter stages of combustion, and whereby it may also besubjected to a combinedair-and-steam blast during the middle portion ofits combustion, or intermediate to the ignition period and latter stagesof combustion, to thereby obviate the formation of elinkers, in a Agreatmeasure, and secure the best practical results in the burning andcombustion of said fuel. As a means for accomplishing this end, I haveshowny a steam-blast apparatus located in one of the air-blast chambersbelow the grate between the ignition region of the furnace, and theregion where the combustion of the fuel is completed. When only threeblast-chambers are used as shown in the drawings, the first air-chambera. will supply the moderatepressure air-blast suitable for igniting thefuel;` the second air-chamber b will supply the high-pressure blastsuitable for forcing the rapid combustion of the fuel, and the thirdair-chamber c will supply the low-pressure air-blast for gently blowingthe nearly consumed fuel during the last stages of the combustionperiod.

The steam-blast apparatus may properly consist of a pipe, 27, extendinginto the airchamber transversely of the furnace and having a series ofperforations in the upper side` thereof through which jets of steamissue upwardly toward the grate, as indicated at 28 in Fig. l ofthedrawings.

The steam-blast apparatus is herein shown as entering the high-pressurechamber b of the air-blast apparatus; the jets of steam issuing fromsaid steam-blast apparatus commingle with and impregnate the air in thehigh-pressure chamber, thus forming a combined air-and-steam blast ofrelatively highpressure to the action of which the fuel is subjectedduring the middle portion of the combustion period.

According to my present process, the fuel is subjected to a low-pressuredry-air blast at the ignition-period, thus insuring a better ignition ofthe fuel than if the steam-blast were supplied to the fuel during theignition-period; and the full effect of the steam-blast is secured forpreventing the formation of elinkers, since this formation only occursafter the fuel has become fully ignited and has reached a state of rapidcombustion. In some cases it may be desirable to use the steamblast inconnection with two or more airblasts of varying pressures, especiallyif more than three air-chambers are used under the grate. The steamblast may also be applied at a point or points intermediate to twoairblasts.

The fuel is supplied to the grate from the hopper lvl through the chuteor opening 5 and is carried forward upon the grate in a layer. The fuelbeing ignited when it first enters the furnace-chamber, the ignition ofthe advancing layer is continued by an air-blast of moderate pressurefrom the first air-blast chamber a. The ignited fuel is carried forwardby the movement of the grate over the second air-blast chamber where itis blown with a relatively high pressure blast of air, or of combinedsteam-and-air if the steam blast apparatus is located at this point asshown in the drawings. The fuel is next carried over the succeedingair-blast apparatus, comprising the chamber c where it is subjected to adry-air" blast of much lower pressure and where the combustion of thefuel is completed, the resultant ash and cinder being discharged overthe rearward end of the grate.

A portion of the process herein` described, t'. e.-that of subjectingthe fuel while spread in a layer to successive air-blasts of varyingpressures is substantially the same process as described and claimed inLetters Patent of the United States No. 499,715, granted to E. B. CoxeJlune 20, 1893. The successive stepsy of the process consist ofignitingthe fuel spread in a layer; subjecting` the same to a dry-air blast ofmoderate pressurefduring the `ignition period; moving the ignited fuelforward and subjecting the same to au air-blast of increased pressureand at the same time, or substantially so,`subjeeting the fuel to asteam-blast, and subsequently carrying the fuel forward and subjectingthe same to a dry-air blast for completing the combustion thereof.

Having thus described my invention, I claim- 1. The herein-describedproeessiof burning fuel,which consists in igniting the mass spread in alayer, subjecting said ignited layer t0 successive air-blasts of varyingpressures during the successive stages of the combustion period, andalso subjecting said mass to a steam-blast between the first and laststages of the combustion thereof, substantially as described.

2. The herein-described process of burning fuel,which consists inigniting the mass spread in a layer, subjecting the same to a dry-airblast during the ignition period, a dry-air blast during the last stagesof the combustion period, and a combined steam-and-air blast near themiddle portion of the combustion period, substantially as described.

3. The herein-described process of burning coal and other fuel, whichconsists in igniting the mass spread in a layer, feeding said massforward subjected to a dry-air blast of relatively low pressure duringthe early part and the latter part of the combustion period andsubjecting said layer to a combined air-and- IOO lIO

-. set forth.

5. The herein described process of burning fuel, which consists inspreading the samein a layer, igniting the layer, moving the layerforward during combustion and subjecting the same during the successiveperiods of combustion to successive dry-air and steamblasts,substantially as described.

6. The herein-described process of burning coal and other fuel, whichconsists in subjecting a moving mass or layer first to heat and to adry-air blast of relatively low pressurefor igniting the same, nextsubjecting the ignited layer to a combined steam-and-air blast ofrelatively high pressure, and subsequently subjecting the burning fuelto a dryair blast of relatively low pressure, substantially as describedand for the purpose set forth.

7. In a furnace, the combination with a traveling grate and withsuccessive air-supply chambers underneath the grate at successive pointsin the length thereof, of means for supplying air to the chambers a'tdifferent pressures, and means for supplying steam to the grate throughone of said chambers, whereby the fuel may be ignited bya dry-air blast,continued burning by a combined air-andsteam blast, and the burningcompleted by a dry-air blast, substantially as described.

8. In a furnace, the combination with a traveling grate and with meansfor supplying the FRANCIS H. RICHARDS.

Witnesses:

FRED. J. DOLE, FREDERICK A. BOLAND.

